*-----------*
|.1.|.8.|.5.|
|2..|...|8..|
|3.5|6..|1..|
|---+---+---|
|...|5.9|.74|
|...|...|...|
|93.|4.7|...|
|---+---+---|
|..7|..6|4.5|
|..3|...|..1|
|.9.|.2.|.6.|
*-----------*